-LOST is by far my favorite show I've ever watched on t.v.
-The Daily Show is a very good second, although I suppose it's better to say the these two shows are in very different classes.
-Myth Busters rocks too.
-I really liked the first two seasons of The Apprentice.
-And I really liked The Amazing Race until they made this "family edition" season. Now I think this season sucks.

edit: Oh, I almost completely forgot Penn & Teller's Bullsh*t. It's on showtime at a really obsure time slot, but thanks to Tivo I can watch every episode. It's a really good show. I think I'd stick it in at #2 or #3 in the list above.

Top Gear is a Brit show about high performance cars, Myth Busters is a couple of hollywood stunt/special effects guys proving/disproving popular myths. I get them both on Discovery. Both typical "guy" shows.